<template>
  <div class="pagination">
    <button :disabled='startEnd.start === 1' @click="$emit('changePage',pageNo-1)">上一页</button>
    <button v-if="startEnd.start !== 1" @click="$emit('changePage',1)">1</button>
    <button v-if="startEnd.start > 2">···</button>

    <button 
        v-for="page in startEnd.end"
        v-if="page >= startEnd.start"
        :class="{active:pageNo === page}"
        @click="$emit('changePage',page)"
    >{{page}}</button>

    <button v-if="startEnd.end < totalPage-1">···</button>
    <button v-if="startEnd.end !== totalPage " @click="$emit('changePage',totalPage)">{{totalPage}}</button>
    <button :disabled='startEnd.end === totalPage' @click="$emit('changePage',pageNo+1)">下一页</button>
    <button style="margin-left: 30px">共 {{total}} 条</button>
  </div>
</template>

<script>
export default {
  name: "Pagination",
  props:{
      //当前页
      pageNo:{
          type:Number,
          default:1
      },
      //每页显示数
       pageSize:{
          type:Number,
          default:1
      },
      //总数
       total:{
          type:Number,
          default:1
      },
      //连续页数
       continuousPage:{
          type:Number,
          default:5
      },
  },
    computed:{
        totalPage(){
            return Math.ceil(this.total / this.pageSize)
        },
        startEnd(){
            let start = 0
            let end = 0
            let {totalPage,continuousPage,pageNo} = this
            if(totalPage <= continuousPage){
                start = 1
                end = totalPage
            }else{
                start = pageNo - Math.floor(continuousPage / 2)
                end = pageNo + Math.floor(continuousPage / 2)
                if(start <=1){
                    start = 1
                    end = continuousPage
                }else if(end >=totalPage){
                    end = totalPage
                    start = end - continuousPage + 1
                }
            }
            return {start,end}
        }
    }
};
</script>

<style lang="less" scoped>
.pagination {
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
}
</style>